Four patients with epidermolysis bullosa acquisita were investigated using immunofluorescence, routine electron microscopic and immunoelectron microscopic techniques. Immunofluorescence studies demonstrated linear immunoglobulin and complement deposition along the dermal-epidermal junction. These findings are similar to those seen in skin of patients with bullous pemphigoid. Immunoelectron microscopic studies demonstrated that the immunoreactants were localized below the subbasal lamina-anchoring fibril zone of the basement membrane, thereby clearly distinguishing the immunopathology of epidermolysis bullosa acquisita from that seen in bullous pemphigoid. Indirect immunoelectron microscopic findings suggest that epidermal basal cells of affected patients may secrete the dermal substances to which the antibodies bind.

In a distinct autosomal recessive variant of epidermolysis bullosa, EB-MD, life-long skin blistering is associated with late-onset muscular dystrophy of unknown etiology. Electron microscopy of these patients' skin suggests that tissue separation occurs intracellularly at the level of the hemidesmosomal inner plaque, which contains plectin, a high molecular weight cytoskeletal associated protein, also expressed in the sarcolemma of the muscle. In this study, we report two patients with EB-MD, each with a homozygous deletion mutation in the plectin gene, PLEC1. In the first case, the proband and her similarly affected sister had a homozygous 9 bp deletion mutation, designated as 2719de19, which resulted in elimination of three amino acids, QEA, in a sequence of 23 amino acids entirely conserved between the mouse and human sequences. The proband in the second family demonstrated a single nucleotide deletion at position 5866, designated as 5866delC, which resulted in frameshift and a premature termination codon for translation 16 bp downstream from the site of deletion. The absence of plectin in the hemidesmosomes, as reflected by negative immunofluorescence with an anti-plectin antibody (HD-1), associated with fragility of basal keratinocytes, implicates plectin as critical for binding of intermediate keratin filament network to hemidesmosomal complexes. The function of plectin as a putative attachment protein also in the muscle would explain the clinical phenotype consisting of cutaneous fragility and muscular dystrophy in EB-MD.

A B S T R A C T Five patients with herpes gestationis, a blistering disease of pregnancy, were studied immunologically. All had in vivo deposition of C3 in a linear band along the basement membrane zone of lesional and normnal-appearing skin, the location of early blister formation. Immunoglobulin deposition was more variable, though four patients had evidence of in vivo bound IgG at the same site. A circulating, complement binding herpes gestationis factor was demonstrated in the sera of four of the patients, its concentration unrelated to the activity of clinical disease. Characterization of this factor by sucrose gradient ultracentrifugation, specific absorption studies, and papain digestion indicates that it is an IgG. Evidence exists for involvement of both the classical and alternate complement pathways in vivo, though in vitro studies implicate the classical pathway as the primary route of complement activation. Three offspring were studied, none with clinical involvement; one slhowed in vivo deposition of C3 at the basement membrane zone of normal skin and a second showed the herpes gestationis factor in cord blood.

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Antibodies to type IV collagen were produced by immunizing rabbits with a basement membrane collagen obtained from a transplantable mouse tumor. Using specifically purified antibodies, type IV collagen was localized ultrastructurally to the basal lamina part of the basement membrane zone.